FWIW — I think MG MOs are on a positive pay system. When MO is presented for payment by depository bank, MG system will validate serial, amount, etc and authorize payment if everything is kosher, otherwise it will not approve for payment. Hopefully they have their act together enough so that stop payment requests are processed real time.
Of course, if your luck is anything like mine, you will find the lost MO as soon as you’re finished with mg.